Every visitor Of a Natural History Museum can trace a likeness between the Animals and Plants shown there and those with which he is already familiar, and he is thus ready to derive pleasure and instruction from their examination. But when he comes to the Minerals, and finds that with life and organised structure has apparently disappeared everything which gives separateness to the individual, and that hardly any distinctive character seems to be left save colour, he becomes impressed with the idea that, while their beauty is evident, minerals must fail Of being discriminated unless we penetrate beyond their superficial aspects.